The present invention relates generally to a device for detecting an arc fault and, more particularly, to a circuit for preventing a malfunction of the arc fault detection device for determining whether an arc fault occurs through a low-current route or a high-current route, classified according to the magnitude of load current, using a source voltage applied to a conductor, which sets an operational prohibition range so as to prevent the malfunction of determining a pseudo-arc signal attributable to various combinations of loads to be an arc signal and interrupting a circuit, thus being capable of more precisely controlling the detection of the arc signal.
As is generally known, an arc fault (series arc, parallel arc, or ground arc), which occurs over electrical wiring, is a phenomenon that occurs due to a physical or electrical fault, such as the aging or damage of wiring, an insulation fault or overcurrent. Such an arc fault particularly causes fires, so that, recently, the use of an arc fault protection interrupter that detects an arc fault and interrupts electric products in a circuit manner have become mandatory in the United States.
One consideration for the detection of an arc fault is to distinguish an arc signal from signals similar thereto, that is, a signal generated at the time of start of electric equipment (hereinafter referred to as a ‘start signal’) and a signal caused by a dimmer (hereinafter referred to as a ‘dimmer signal’).
A conventional arc fault detector occasionally interrupts a circuit because it mistakes a start or dimmer signal, which is a pseudo-arc signal, for an actual arc fault signal.
Accordingly, in order to prevent such a mistake, efforts have been concentrated on producing an arc fault detector that can distinguish a pseudo-arc signal from an actual arc signal and then interrupt a circuit.
However, a commercially available product can detect an arc signal using a scheme of detecting current flowing through a connector between a power source and a load and determining whether an arc fault occurs, but still allows the possibility that signals similar to the above-described arc signal are also detected and, thus, a malfunction occurs. Furthermore, the conventional arc fault detector detects the arc signal through a single route without distinguishing low current from high current, so that many problems occur at the time of setting a frequency band and circuit interruption time (the interval between the time at which an arc occurs and the time at which a circuit is interrupted).
In other words, the conventional arc fault detector is available commercially in the form of a product using a scheme of detecting parallel and ground arcs that occur due to a large load current and then interrupting a circuit, but is not available commercially in the form of a product using a scheme of detecting an arc below the rated current of an interrupter and then interrupting a circuit.
The reason for this is that load signals similar to the arc signal are various, and the frequency and magnitude of a detected signal vary according to the connection of a plurality of loads, not a single load, so that it is difficult to distinguish the pseudo-arc signals from an actual arc signal, therefore the circuit interruption time, based on arc generation, increases.
Accordingly, in order to solve this problem, Korean Unexamined Pat. Appl. No 10-2004-59272 was filed by the present applicant.
The technology relates to an arc fault detection device that can eliminate a malfunction attributable to the conventional current detection scheme by detecting source voltage applied to a conductor and determines whether an arc faults occur, and can not only prevent malfunctions caused by pseudo-arc signals but also shortening the circuit interruption time according to the size of a load by determining whether arc faults occur through two routes classified according to the magnitude of load current, thus considerably reduce the danger of fire.
Accordingly, due to the advent of this technology, advanced technology that easily detects an arc occurring below a rated value as well as a high load current above the rated value and quickly interrupt a circuit has been provided.
The present invention is combined with the above-described technologies, and is a technology for eliminating the malfunction of determining a pseudo-arc signal attributable to various (a plurality of) combinations of loads to be an actual arc signal and interrupting a circuit, that is, a malfunction of an interrupter that occurs due to unnecessary tripping.